Add functionality to be able to set default values to metadata

Author: LogicalError

Editor/Common/AssetMetadataUtility.cs

@@ -149,7 +149,8 @@ public static CustomAssetMetadata Add(UnityEngine.Object target, Type type)
         {
 			assetMetadata.name = type.Name;
             assetMetadata.reference = target;
-            AssetDatabase.AddObjectToAsset(assetMetadata, assetPath);
+            assetMetadata.OnReset();
+			AssetDatabase.AddObjectToAsset(assetMetadata, assetPath);
             AssetDatabase.ImportAsset(assetPath);
             AssetDatabase.Refresh();
             return assetMetadata;

Runtime/Baseclass/CustomAssetMetadata.cs

@@ -10,4 +10,6 @@ public abstract class CustomAssetMetadata : ScriptableObject
 	// These methods are to handle creating and destroying metadata in the editor and not leave the asset dangling
 	[Conditional("UNITY_EDITOR")] private void OnEnable() { if (Application.isEditor && reference.isSet && !reference.isBroken) MetadataLookup.Register(reference, this); }    
     [Conditional("UNITY_EDITOR")] private void OnDisable() { if (Application.isEditor && reference.isSet && !reference.isBroken) MetadataLookup.Unregister(reference, this); }
+
+	public virtual void OnReset() { }
 }